This invention relates to a DC power supply having feedback circuits for load voltage regulation and overload protection.
DC power supplies are known which use a switching transistor to pass current pulses to a filter network such as a series choke inductor for smoothing the gated current pulses. A feedback network controls the switching period of the transistor to maintain a high degree of voltage regulation and low output ripple. It has been known to protect the switching transistor from high voltage pulses created by the choke inductor by use of a blocking diode, such as shown by U.S. Pat. No. 3,068,392 to Santelmann, Jr. It is also known to use the high voltage pulses created by the choke inductor to control regulation by causing the transistor to conduct in a manner which follows a reference voltage, as shown in U.S. Pat. No. 3,246,229 to Lloyd.
In power supplies using a choke inductor and a switching device, it would be desirable to provide a simplified overload protection circuit which is responsive to the actual load current. Such a device should desirably require a minimum number of components, and should not be placed in series with the switching device. Furthermore, it would be preferable to have a common ground between the unregulated supply and the regulated output. It also would be desirable to provide improved regulation of the switching device in accordance with the sensed load current.